Aggarwal Vishnu, Abidi Irfan H, Limb Jake, Kofler Clara, Verma Ajay Kumar, Giridhar Sindhu Priya, Dissanayake Nethmi S L, Vashishtha Pargam, Tollerud Jonathan O, Mao Jianfeng, Sehrawat Manoj, Gupta Tanish, Kannan Boopathiraja, Panahandeh-Fard Majid, Ahmed Taimur, Lu Yuerui, Davis Jeffrey A, Russo Salvy P, Kotakoski Jani, Della Gaspera Enrico, Bentley Cameron L, Kushvaha Sunil Singh, Walia Sumeet
Centre for Optoelectronic Materials and Sensors (COMAS), School of Engineering, RMIT University, 124 La Trobe Street, Melbourne, Victoria 3001, Australia.
CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India.
ACS Appl Mater Interfaces. 2025 Aug 27;17(34):48658-48669. doi: 10.1021/acsami.5c11713. Epub 2025 Aug 12.
The stacking orientation of bilayer two-dimensional (2D) materials introduces an additional degree of freedom that can profoundly influence their electronic, optoelectronic, and electrochemical properties. While stacking-engineered phenomena such as ferroelectricity, superconductivity, and second harmonic generation have been widely studied in bilayer molybdenum disulfide (MoS), their impact on functional device performance, particularly photoresponse and electrocatalysis, remains largely unexplored. Here, we investigate how the stacking configuration governs the optoelectronic and electrocatalytic behavior of bilayer MoS, focusing on the two stable stacking orders: 2H and 3R synthesized via chemical vapor deposition (CVD). Photodetection measurements reveal that 2H stacked bilayer MoS exhibits a remarkable two-orders-of-magnitude enhancement in photoresponsivity over its 3R counterpart, attributed to stronger interlayer coupling and more efficient charge transfer. Additionally, 2H MoS demonstrates enhanced field-effect transistor (FET) characteristics and achieves twice the hydrogen evolution reaction (HER) activity compared to 3R MoS. We employ scanning electrochemical cell microscopy (SECCM) to achieve spatially resolved mapping of electrocatalytic reactivity, offering the first direct nanoscale visualization of stacking-dependent HER activity. These findings underscore the crucial role of stacking orientation of atomic layers in tuning both optoelectronic and electrocatalytic properties, paving the way for stacking-engineered 2D materials in next-generation photodetectors and electrocatalytic devices.
双层二维（2D）材料的堆叠取向引入了一个额外的自由度，这可以深刻影响其电子、光电和电化学性质。虽然诸如铁电性、超导性和二次谐波产生等堆叠工程现象已在双层二硫化钼（MoS）中得到广泛研究，但它们对功能器件性能的影响，特别是光响应和电催化，在很大程度上仍未被探索。在此，我们研究堆叠构型如何控制双层MoS的光电和电催化行为，重点关注通过化学气相沉积（CVD）合成的两种稳定堆叠顺序：2H和3R。光探测测量表明，与3R堆叠的双层MoS相比，2H堆叠的双层MoS的光响应度显著提高了两个数量级，这归因于更强的层间耦合和更有效的电荷转移。此外，与3R MoS相比，2H MoS表现出增强的场效应晶体管（FET）特性，并且析氢反应（HER）活性提高了一倍。我们采用扫描电化学细胞显微镜（SECCM）来实现电催化反应性的空间分辨映射，首次直接在纳米尺度上可视化了堆叠依赖的HER活性。这些发现强调了原子层堆叠取向在调节光电和电催化性质方面的关键作用，为下一代光探测器和电催化器件中堆叠工程二维材料的应用铺平了道路。
